Detection of Senecavirus A in pigs from a historically negative national swine herd and associated with feed imports from endemically infected countries

Since the initial report of the ability of contaminated feed to transmit porcine epidemic diarrhoea virus (Dee et al., 2014), further proof regarding the risk of feed and feed ingredients to the spread of viruses—includingAfrican swine fever virus, classical swine fever virus, foot and mouth disease virus, and pseudorabies virus—has been published (Niederwerder et al., 2019; Stenfeldt et al., 2022; Stoian et al., 2020). Another viral pathogen, Senecavirus A (SVA), also has been shown to survive well in feed, and can be transmitted to pigs following natural feeding behaviour (Caserta et al., 2022; Dee et al., 2018). As an example of its stability and long-term infectivity in feed, SVA remained infectious to pigs following a 23-day, 10,800-km transport of virus-positive feed across 29 states of the continental United States (Dee et al., 2022). SVA is a single-stranded, non-enveloped RNA virus within the same virus family as foot and mouth disease virus (FMDV) and can cause vesicular lesions in pigs that are visibly indistinguishable to those caused by FMDV (Joshi & Diel, 2015). Following observation of vesicles, once a differential diagnosis of SVA has been confirmed, the presence of SVA in pig populations does not prohibit the sale or export of pork meat and pork products. The risk of feed and feed ingredients for the spread of viruses of veterinary significance is a relatively new discovery; since it previously was thought not to occur, it has been ignored at the level of the classroom, the farm, government administration, global animal health organizations, and elected officials. Therefore, the purpose of this Research News is to describe the initial clinical diagnosis of SVA in a swine farm from a historically naïve national herd, and the results of a diagnostic investigation designed to


feed, imported, ingredients, naïve, Senecavirus A, swine
Since the initial report of the ability of contaminated feed to transmit porcine epidemic diarrhoea virus (Dee et al., 2014), further proof regarding the risk of feed and feed ingredients to the spread of viruses-including African swine fever virus, classical swine fever virus, foot and mouth disease virus, and pseudorabies virus-has been published (Niederwerder et al., 2019;Stenfeldt et al., 2022;Stoian et al., 2020). Another viral pathogen, Senecavirus A (SVA), also has been shown to survive well in feed, and can be transmitted to pigs following natural feeding behaviour (Caserta et al., 2022;Dee et al., 2018).
As an example of its stability and long-term infectivity in feed, SVA remained infectious to pigs following a 23-day, 10,800-km transport of virus-positive feed across 29 states of the continental United States . SVA is a single-stranded, non-enveloped RNA virus within the same virus family as foot and mouth disease virus (FMDV) and can cause vesicular lesions in pigs that are visibly indistinguishable to those caused by FMDV (Joshi & Diel, 2015). Following observation of vesicles, once a differential diagnosis of SVA has been confirmed, the presence of SVA in pig populations does not prohibit the sale or export of pork meat and pork products. The risk of feed and feed ingredients for the spread of viruses of veterinary significance is a relatively new discovery; since it previously was thought not to occur, it has been ignored at the level of the classroom, the farm, government administration, global animal health organizations, and elected officials. Therefore, the purpose of this Research News is to describe the initial clinical diagnosis of SVA in a swine farm from a historically naïve national herd, and the results of a diagnostic investigation designed to This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2022 The Authors. Transboundary and Emerging Diseases published by Wiley-VCH GmbH.
identify potential routes of entry of SVA to the country and the farm.
For confidentiality, names of all countries and companies will not be disclosed in this report.
In July 2022, vesicular lesions were observed on the snouts and feet of pigs in the case of a pork production system. Diagnostic testing indicated the presence of SVA in vesicular fluids and also ruled out the presence of FMDV. Prior to the onset of clinical signs, feed ingredients had been imported from other countries, several of which were known to be endemically infected with SVA, and formulated diets containing these imported ingredients were being fed to pigs prior to and during the onset of clinical signs. All feed ingredients had been stored in a warehouse at the feed mill, which was located at a separate site from the farm, and different personnel worked at the mill and at the farm. As this was the first case of SVA in the national swine herd, a diagnostic investigation was conducted to identify potential sources of viral entry. Published methods were used to detect viruses in dust samples collected from environmental surfaces at the affected farm, and dust samples and grain probe samples from feed ingredients and environmental surfaces at the feed mill Gebhardt et al., 2022;Khanal et al., 2022). A total of 39 samples were collected, including eight dust samples from facilities and equipment, that is, floor surfaces from storage warehouses and associated driveways on affected farms and mills, along with feed mixers. In addition, 13 dust and probe samples were collected from bulk-feed ingredients, including a mixture of soybean meal imported from one SVA-positive and two SVAnegative countries, along with raw soybeans and corn gluten meal from  and support the adoption of Responsible Imports practices to manage this risk (Patterson et al., 2019). Fortunately, this was SVA, and not FMDV; however, it might not be the case next time.
conducted the sampling and shared the data. Hopefully, full disclosure will take place later.

CONFLICT OF INTEREST
The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT
The data are available on reasonable request from the corresponding author

ETHICS STATEMENT
This report did not involve the use of experimental animals for research. Rather, it contains a summary of a diagnostic investigation conducted by employees from a specific production system who oversee the ethical raising of pigs in commercial facilities.